Full Product Description
Frequency Response Measurement & Correction
The RAAL requisite CA-1a is a ribbon headphone. Depending on which earpad is used, produces a significantly different sonic signature. While the closed earpads produce a reasonably smooth response up to 1 kHz, there is a significant wide band -8 dB dip in frequency response from about 1.5 kHz to 5 kHz. This results in a very dark sound.
While the open earpads aren’t as dark sounding, there is a lack of deep bass response with a 1.2 kHz peak and then another -6dB dip in frequency response between 1.5 and 3.5 kHz, right where out ears are the most sensitive. The rising narrow band peak at 5 kHz gives the headphone the impression of being a bit brighter than the closed earpads, but still very midrange-y sounding.
With the addition of the phase response chart, the CA-1a have phase issues that obfuscate the clarity and depth of field that these headphones are capable of.
Engaging the high-resolution convolution filter is indeed a “night and day” difference in sonic signature of these headphones. With the convolution filter engaged, using either set of earpads, the response is ruler flat from 15 Hz to 5 kHz +- 0.5 dB. The convolution filters fully optimize the ribbon design and manufacture of these headphones.